On Wed, Jun 15, 2022 at 9:57 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
>
> Since ACPICA commit f005ee6b90d1 / Linux commit 2d3349de8072
> ("ACPICA: Namespace: Reorder \_SB._INI to make sure it is evaluated
> before _REG evaluations") acpi_initialize_objects() calls \_SB._INI
> before executing _REG OpRegion methods, because the _REG methods may
> rely on initialization done by this _INI method.
>
> In many DSDTs the \_SB.PC00._INI / \_SB.PCI0._INI methods set an OSYS
> global variable based on _OSI evaluations.
>
> In some cases there are _REG methods which depend on the OSYS value and
> before this change ACPICA would run these _REG methods before running
> _SB.PC00._INI / \_SB.PCI0._INI causing issues.
>
> 2 examples of problems caused by running _REG methods before these
> _INI methods are:
>
> 1. on a "Lenovo IdeaPad 5 15ITL05" \_SB.PC00.LPCB.EC0._REG gets
> evaluated before \_SB.PC00._INI and that _REG contains:
>
> If ((OSYS == 0x07DF))
> {
> Local0 = 0x06
> }
>
> If ((Acquire (LFCM, 0xA000) == Zero))
> {
> OSTY = Local0
> ...
>
> With OSTY being a SystemMemory OpRegion field, due to the _INI running
> too late, Local0 stays at 0. Causing OSTY to be set to 0 instead of 6,
> which causes the brightness up/down keys to not work:
> https://bugzilla.kernel.org/show_bug.cgi?id=214899
>
> 2. On a "Lenovo Thinkbook 14-ILL" \\_SB_.PCI0.I2C0._REG gets
> evaluated before \_SB.PCI0._INI and that _REG contains:
>
> If ((OSYS == 0x07DF))
> {
> ...
> LNUX = Zero
> TPID = 0x4E
> }
> else
> {
> LNUX = One
> TPID = 0xBB
> }
>
> And then later on the TPID value gets used to decide for which of multiple
> devices describing the touchpad _STA should return 0xF and the one which
> gets enabled by TPID=0xBB is broken, causing to the touchpad to not work:
> https://bugzilla.redhat.com/show_bug.cgi?id=1842039
>
> Fix these issues by adding \_SB.PC00._INI / \_SB.PCI0._INI to the list of
> _INI methods to run early (before executing _REG methods).
...
> - char path[ACPI_PATH_SEGMENT_LENGTH + 2];
> + char path[ACPI_PATH_SEGMENT_LENGTH * 2 + 2];
Strictly speaking this should be, IIUC,
1 + ACPI_PATH_SEGMENT_LENGTH + ACPI_NAMESEG_SIZE + 1
\\ + path segment length (with a separator) + name + \0
That said, it seems the original code adds 1 unneeded byte.
Perhaps a comment in the code?
--
With Best Regards,
Andy Shevchenko
